using System;
using System.Text;

using Org.BouncyCastle.Utilities;

namespace Org.BouncyCastle.Asn1
{
	/**
	 * Der VisibleString object.
	 */
	public class DerVisibleString
		: DerStringBase
	{
		private readonly string str;

		/**
		 * return a Visible string from the passed in object.
		 *
		 * @exception ArgumentException if the object cannot be converted.
		 */
		public static DerVisibleString GetInstance(
			object obj)
		{
			if (obj == null || obj is DerVisibleString)
			{
				return (DerVisibleString)obj;
			}

			if (obj is Asn1OctetString)
			{
				return new DerVisibleString(((Asn1OctetString)obj).GetOctets());
			}

			if (obj is Asn1TaggedObject)
			{
				return GetInstance(((Asn1TaggedObject)obj).GetObject());
			}

			throw new ArgumentException("illegal object in GetInstance: " + obj.GetType().Name);
		}

		/**
		 * return a Visible string from a tagged object.
		 *
		 * @param obj the tagged object holding the object we want
		 * @param explicitly true if the object is meant to be explicitly
		 *              tagged false otherwise.
		 * @exception ArgumentException if the tagged object cannot
		 *               be converted.
		 */
		public static DerVisibleString GetInstance(
			Asn1TaggedObject	obj,
			bool				explicitly)
		{
			return GetInstance(obj.GetObject());
		}

		/**
		 * basic constructor - byte encoded string.
		 */
		public DerVisibleString(
			byte[] str)
			: this(Strings.FromAsciiByteArray(str))
		{
		}

		/**
		 * basic constructor
		 */
		public DerVisibleString(
			string str)
		{
			if (str == null)
				throw new ArgumentNullException("str");

			this.str = str;
		}

		public override string GetString()
		{
			return str;
		}

		public byte[] GetOctets()
		{
			return Strings.ToAsciiByteArray(str);
		}

		internal override void Encode(
			DerOutputStream derOut)
		{
			derOut.WriteEncoded(Asn1Tags.VisibleString, GetOctets());
		}

		protected override bool Asn1Equals(
			Asn1Object asn1Object)
		{
			DerVisibleString other = asn1Object as DerVisibleString;

			if (other == null)
				return false;

			return this.str.Equals(other.str);
		}

		protected override int Asn1GetHashCode()
		{
			return this.str.GetHashCode();
		}
	}
}
